1. Field of the Invention
The present invention relates to a coordinate measuring machine with a base frame which is essentially constructed in the mode of a portal or gantry-type structure which concurrently forms a measuring table, and with a cross-carrier which spans over the measuring table and receives a measuring carriage with a spindle, and which supports itself with one arm on a guideway located in front of the measuring table
2. Discussion of the Prior Art
A coordinate measuring machine of the type which is under consideration herein is already presently known from the disclosure of German Patent Specification 31 25 681 C2. In this known coordinate measuring machine, the base frame is constituted from at least one molded synthetic resin-concrete component into which the steel guideways are inserted. Thereby, the composition of the synthetic resin-concrete is selected in a manner in the region of the steel guideways, such that the thermal coefficient of expansion thereof generally conforms with that of the steel guideways. Extending from the measuring table, the base frame possesses an axial or longitudinal tie bar which is located high above the measuring table, and into which there is inserted the guideway for the bearing support or pedestal of the cross-carrier. This causes problems to the extent in that already relatively minute deformations, which can be caused by the weight of workpiece which is to be measured on the measuring table, are transmitted through the lengthy level arms of the portal or gantry supports into the guideways, which can lead to swayings of the guideways and, as a consequence, to uncertainties in the accuracy of measurement. In addition thereto, with this type of construction of a coordinate measuring machine constituted from a synthetic resin-concrete, there must be considered that this machine cannot be highly stressed from a thermal standpoint.
As a result thereof, any temperature overloading can lead throughout to deformations of the base frame and the support arms, as well as the carrie.